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Proportion word problems

It is very important to notice that if the ratio on the left is a ratio of number of liters of water to number of lemons, you have to do the same ratio on the right before you set them equal. 

More interesting proportion word problems

Check this site if you want to solve more proportion word problems.

Ratio word problems

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Solving Proportions: Word Problems

Ratios Proportions Proportionality Solving Word Problems Similar Figures Sun's Rays / Parts

Many "proportion" word problems can be solved using other methods, so they may be familiar to you. For instance, if you've learned about straight-line equations, then you've learned about the slope of a straight line, and how this slope is sometimes referred to as being "rise over run".

But that word "over" gives a hint that, yes, we're talking about a fraction. And this means that "rise over run" can be discussed within the context of proportions.

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You are installing rain gutters across the back of your house. The directions say that the gutters should decline katex.render("\\small{ \\bm{\\color{green}{ \\frac{1}{4} }}}", typed01); 1 / 4 inch for every four feet of lateral run. The gutters will be spanning thirty-seven feet. How much lower than the starting point (that is, how much lower than the high end) should the low end of the gutters be?

Rain gutters have to be slightly sloped so the rainwater will drain toward and then down the downspout. As I go from the high end of the guttering to the low end, for every four-foot length that I go sideways, the gutters should decline [be lower by] one-quarter inch. So how much must the guttering decline over the thirty-seven foot span? I'll set up the proportion, using " d " to stand for the distance I'm needing to find.

There is a variable in only one part of my proportion, so I can use the shortcut method to solve.

d = [(37)(1/4)]/4

For convenience sake (because my tape measure isn't marked in decimals), I'll convert this answer to mixed-number form:

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As is always the case with "solving" exercises, we can check our answers by plugging them back into the original problem. In this case, we can verify the size of the "drop" from one end of the house to the other by checking the products of the means and the extremes (that is, by confirming that the cross-multiplications match) of the completed proportion:

(1/4)/4 = 2.3125/37

Converting the "one-fourth" to " 0.25 ", we get:

(0.25)(37) = 9.25

(4)(2.3125) = 9.25

Since the values match, then the proportionality must have been solved correctly, and the solution must be right.

Biologists need to know roughly how many fish live in a certain lake, but they don't want to stress or otherwise harm the fish by draining or dragnetting the lake. Instead, they let down small nets in a few different spots around the lake, catching, tagging, and releasing 96 fish. A week later, after the tagged fish have had a chance to mix thoroughly with the general population, the biologists come back and let down their nets again. They catch 72 fish, of which 4 are tagged. Assuming that the catch is representative, how many fish live in the lake?

As far as I know, biologists and park managers actually use this technique for estimating populations. The idea is that, after allowing enough time (it is hoped) for the tagged fish to circulate throughout the lake, these fish will then be evenly mixed in with the total population. When the researchers catch some fish later, the ratio of tagged fish in the sample to untagged is representative of the ratio of the 96 fish that they tagged with the total population.

I'll use " f " to stand for the total number of fish in the lake, and set up my ratios with the numbers of "tagged" fish on top. Then I'll set up and solve the proportion:

Because the variable is in only one part of the proportion, I can use the shortcut method to solve.

f = [(96)(72)]/4

This tells me that the estimated population is:

about 1,728 fish

Another type of "proportion" word problem is unit conversion, which looks like this:

How many feet per second are equivalent to 60 mph?

To complete this exercise, I will need conversion factors, which are just ratios. (If you're doing this kind of problem, then you should have access — in your textbook or in a handout, for instance — to basic conversion factors. If not, then your instructor is probably expecting that you have these factors memorized.)

I'll set everything up in a long multiplication so that the units cancel :

88 feet per second

Take note of how I set up the conversion factors for my multiplicate (above) in not-necessarily-standard ways. For instance, one usually says "sixty minutes in an hour", not "one hour in sixty minutes". So why did I enter the hour-minute conversion factor (in the second line of my computations above) as "one hour per sixty minutes"?

Because doing so lined up the fractions so that the unit of "hours" in my conversion factor would cancel off with the "hours" in the original " 60 miles per hour". This cancelling-units thing is an important technique, and you should review it further if you are not comfortable with it.

A particular cookie recipe calls for 225 grams of flour for one batch of thirty cookies. Jade would like to make as many cookies as possible for the upcoming block party, and flour is his only constraint (he's got loads of sugar, eggs, etc). If he has 1.206 kilograms of flour, and assuming that all cookies are the same size, approximately how many cookies can he make? (Round to an appropriate whole number.)

I've got two elements here for my proportion: grams of flour and number of cookies. I got to "grams" first when reading the exercise, so I'll put "grams" on top in my proportion.

Since the relationship is given to me in terms of grams, not kilograms, I'll need to convert Jade's on-hand measure to " 1,206 grams, also. I'll use " c " to stand for the number that I'm trying to figure out for "cookies".

(grams)/(cookies): 225/30 = 1206/ c

Since I have an unknown in only one spot in this proportion, I can use the shortcut method to solve.

c = [(1206)(30)]/225

c = 36180/225

Ohhh! Now I see why the instructions said to round to an "appropriate" whole number: Jade can only make whole cookies; the "point-eight" of a cookie will be an undersized niblet that he'll eat before heading to the party.

While normally I'd round this number up to get my whole-number answer, in this case I need to round down ; in other words, in this context (namely, of all the cookies being the same size), I have to ignore the fractional portion (that is, the point-eight decimal part) to get the desired answer.

160 cookies

Kumar lives in Croatia, and is visiting relatives in India. The current exchange rate is one Euro ( €1 ) to 80.45 Indian rupees ( ₹80.45 ). He wants to buy a gift for them, which costs ₹3,759 . How many Euros will this gift cost him? (State your answer accurate to two decimal places.)

They've given me an exchange rate, which is, effectively, just another conversion factor, like the "miles per hour" exercise above. So I'll set up my proportion, with Euros on top, and will use e to stand for the number of Euros he'll need.

(Euros)/(Rupees): 1/80.45 = e /3759

I'll use the shortcut method to solve:

e = [(3759)(1)]/80.45

e = 46.72467371...

Rounding to two decimal places, Kumar will be spending:

€46.72

Other than for the rate-conversion exercise above, we've been able to solve all of the proportions by the shortcut method. You will likely find this to be the case in your homework, also. But it is always possible that you'll get a question where you'll be better off using cross-multiplication instead.

George has heard from two different sources about the pay range at a particular company. One source says that the ratio of lowest pay to highest pay is 3 : 7 . The other source says that the top earner annually makes about $57,000 more than the lowest earner. What are the approximate salaries for the highest and lowest earners? (Round to the nearest thousand.)

I know that the ratio is 3 : 7 , so I'll be using the fraction 3/7 for one side of my proportion. If the lowest pay rate, in thousands of dollars, is L , then the highest is L  + 57 . My proportion is:

(lowest)/(highest): 3/7 = L /( L + 57)

Because there are variables in two of the parts of this proportion, the shortcut method won't be as useful as cross-multiplication to clear all the fractions. So I'll cross-multiply:

3/7 = L /( L + 57)

3( L + 57) = 7 L

3 L + 171 = 7 L

Remembering that I dropped the trailing zeroes and am counting by thousands, the above number means that the lowest salary is (rounded to the nearest thousand) approximately $43,000 . Then the highest salary, being around $57K more, is approximately $100,000 .

lowest: $43,000 highest: $100,000

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How Do You Solve a Word Problem Using a Proportion?

This tutorial provides a great real world application of math. You'll see how to use the scale from a blueprint of a house to help find the actual height of the house. This tutorial shows you how to use a proportion to solve!

• word problem
• translate words to algebra
• cross multiplication
• means extremes

Background Tutorials

Ratio definitions.

What's a Ratio?

Ratios are everywhere! The scale on a map or blueprint is a ratio. Ingredients sometimes need to be mixed using ratios such as the ratio of water to cement mix when making cement. Watch this tutorial to learn about ratios. Then think of some ratios you've encountered before!

Determining Proportionality

What's a Proportion?

The idea of proportions is that a ratio can be written in many ways and still be equal to the same value. That's why proportions are actually equations with equal ratios. This is a bit of a tricky definition, so make sure to watch the tutorial!

Evaluating Expressions

What is a Variable?

You can't do algebra without working with variables, but variables can be confusing. If you've ever wondered what variables are, then this tutorial is for you!

Further Exploration

Solving proportions.

How Do You Set Up a Proportion from a Word Problem?

Sometimes the hardest part of a word problem is figuring out how to turn the words into an equation you can solve. This tutorial let's you see the steps to take in order to turn a word problem involving a blueprint into a proportion. Take a look!

How Do You Solve a Proportion Using Cross Products?

Want to solve a percent proportion? Just use the means extremes property of proportions to cross multiply! Solve for the variable, and you have your answer! Learn how with this tutorial.

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Solving Proportions Word Problems - Examples & Practice - Expii

Solving proportions word problems - examples & practice, explanations (3), proportions in word problems.

The first step in solving any word problem is translating it from words to mathematical expressions.

Image source: By Clker-Free-Vector-Images CC0 via pixabay.com

Let's start by writing a fraction to represent the ratio of mammals to reptiles in the zoo.

What does this fraction look like?

Related Lessons

Proportion Word Problem Walk-through

We're going to walk through a word problem dealing with proportions!

Mark Trumbo of the Arizona Diamondbacks has hit five home runs in the thirty-five times he has been up to bat. At this pace, how many at bats would he need to hit twenty-three home runs?

We want to set up a ratio here. Let's choose: Home Runs(HR):At Bats(AB) So our proportion will be in the form: HRAB=HRAB The first bit of information is that he hit five home runs in the thirty-five times he has been up to bat. Therefore, the first ratio of our proportion will be 535=HRAB For our second proportion we want to know how many at bats would he need to hit twenty-three home runs. The home runs are 23 and the at bats are unknown. 535=23x From here we can just take the cross product and solve.

Remember to simplify your fractions !

Image source: by Hannah Bonville

Finally, we state our answer. He would need to be at bat 161 timesto hit 23 home runs.

Rate Word Problems

To solve this word problem, we need to figure out how many words Kayla can type per minute.

The word per is a trigger, telling you that we are going to be working with ratios and rates .

How many words can Kayla type in one minute?

45 words

52 words

63 words

66 words

Mastering Proportion Word Problems: A Step-by-Step Guide

• Author: Noreen Niazi
• Last Updated on: March 28, 2024

Proportion can be defined as equations that shows two ratios are equivalent to each other’s.  Either you are cooking something, or you are measuring anything, you often need concept of the proportion.  Daily use and practical applications developed many proportion word problems.  Here in this post, I will discuss some effective methods to solve proportion word problems and also gives there practical usage. 

Let’s dive into what is proportion and how to solve proportion word problems and solve top 20 proportion word problems in 2024.

Introduction to proportion word problems

Proportion word problems are a type of math problem that involves finding the relationship between two or more ratios. Ratios are a way of comparing two quantities or values. For example, if you have 4 red marbles and 6 blue marbles, the ratio of red to blue marbles is 4:6 or, simplified, 2:3. Proportion word problems often involve finding missing values in a ratio or comparing two ratios.

Understanding the concept of proportion

Before we dive into the steps to solve proportion word problems, it’s important to understand what proportion means. Proportion refers to the relationship between two or more ratios that are equal. In other words, if two ratios are proportional, they have the same value.

For example, if the ratio of boys to girls in a class is 3:5 and the ratio of students who brought lunch from home to those who bought lunch at school is 2:7, we can compare these two ratios to see if they are proportional. 

We can do this by cross-multiplying and simplifying the fractions. If the resulting fractions are equal, the ratios are proportional. In this case, the cross-products would be 3 times 7 and 5 times 2, simplifying to 21 and 10. Since 21/10 is equal to 3/5, the ratios are proportional.

Steps to solve proportion word problems

Now that we have a solid understanding of proportion, let’s break down the steps to solve proportion word problems:

• Identify the ratios involved in the problem.
• Determine if the ratios are proportional by cross-multiplying and simplifying.
• If the ratios are proportional, use the cross-products to find the missing value(s).
• If the ratios are not proportional, try to find a common multiple to make them proportional.
• Use the cross-products to find the missing value(s) once the ratios are proportional.

Let’s walk through an example problem to see these steps in action.

Example Proportion Word problems with solutions

Example problem: A recipe for brownies calls for 2 cups of flour and 1 cup of sugar. If you want to make a double batch of brownies, how much sugar do you need?

• Identify the ratios involved: 2 cups of flour to 1 cup of sugar.
• Determine if the ratios are proportional: 2:1 and 4:? (since we want to double the recipe). Cross-multiplying gives us 2 times x = 1 times 4, or 2x = 4. Simplifying, we get x = 2. Since 2:1 and 4:2 are equal, the ratios are proportional.
• Use the cross-products to find the missing value: 2 times 2 = 4. Therefore, we need 4 cups of sugar to make a double batch of brownies.

Common mistakes to avoid when solving proportion word problems

While the steps to solve proportion word problems may seem straightforward, there are some common mistakes to watch out for:

• Need to simplify the ratios after cross-multiplying.
• Using the wrong value for a ratio (for example, using 2 instead of 1/2).
• Check if the ratios are proportional before using the cross-products.
• Forgetting to label the units of measurement for the missing value.

By being mindful of these mistakes, you can confidently avoid errors and solve proportion word problems.

Tips to improve your proportion word problem-solving skills

In addition to avoiding common mistakes, there are some tips you can use to improve your proportion word problem-solving skills:

• Practice, practice, practice! The more problems you solve, the more comfortable you will become with proportion.
• Break down the problem into smaller parts. Sometimes it can be helpful to focus on one ratio at a time and combine them at the end.
• Use diagrams or pictures to help visualize the problem.
• Check your work! Double-check your calculations and make sure your answer makes sense in the context of the problem.

Practice problems for mastering proportion word problems

To help you practice and master proportion word problems, here are some sample problems to try:

• A recipe for chocolate chip cookies calls for 2 cups of flour and 1/2 cup of chocolate chips. If you want to make a triple batch of cookies, how many chocolate chips do you need?
• The ratio of boys to girls in a math class is 4:7. If there are 24 students, how many girls are there?
• A map has a scale of 1 inch to 10 miles. If two cities on the map are 3 inches apart, how far are they in real life?

Resources for further practice and learning

If you’re looking for additional resources to practice and improve your proportion word problem-solving skills, here are some options:

• Online practice problems and quizzes on websites like Khan Academy or Math Playground .
• Math workbooks or textbooks with sections on proportion word problems.
• Hiring a tutor or working with a classmate or teacher to get personalized help.

Real-life examples of proportion word problems

Proportion word problems can be found in a variety of real-life situations, such as:

• Cooking and baking recipes that require adjusting ingredient amounts for different serving sizes.
• Scaling maps or blueprints for construction or design projects.
• Calculating proportions of ingredients in chemical reactions or solutions.

By understanding and mastering proportion word problems, you will be better equipped to handle these types of situations in your daily life.

Proportion word problems may seem intimidating initially, but with the right approach and practice, anyone can learn to solve them. By following the steps outlined in this guide, avoiding common mistakes, and using helpful tips and practice problems, you can improve your proportion word problem-solving skills and gain confidence in your mathematical abilities. So the next time you encounter a proportion word problem, don’t be intimidated – tackle it with the skills and knowledge you’ve gained from this guide.

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Ratio problem solving

Here you will learn about ratio problem solving, including how to set up and solve problems. You will also look at real life ratio word problems.

Students will first learn about ratio problem solving as part of ratio and proportion in 6 th grade and 7 th grade.

What is ratio problem solving?

Ratio problem solving is a collection of ratio and proportion word problems that link together aspects of ratio and proportion into more real life questions. This requires you to be able to take key information from a question and use your knowledge of ratios (and other areas of the curriculum) to solve the problem.

A ratio is a relationship between two or more quantities. They are usually written in the form a : b where a and b are two quantities. When problem solving with a ratio, the key facts that you need to know are:

• What is the ratio involved?
• What order are the quantities in the ratio?
• What is the total amount / what is the part of the total amount known?
• What are you trying to calculate ?

As with all problem solving, there is not one unique method to solve a problem. However, this does not mean that there aren’t similarities between different problems that you can use to help you find an answer.

The key to any problem solving is being able to draw from prior knowledge and use the correct piece of information to allow you to get to the next step and then the solution.

Let’s look at a couple of methods you can use when given certain pieces of information.

When solving ratio word problems, it is very important that you are able to use ratios. This includes being able to use ratio notation.

For example, Charlie and David share some sweets in the ratio of 3 : 5. This means that for every 3 sweets Charlie gets, David receives 5 sweets.

Charlie and David share 40 sweets, how many sweets do they each get?

You use the ratio to divide 40 sweets into 8 equal parts.

40 \div 8=5

Then you multiply each part of the ratio by 5.

3\times 5:5\times 5=15 : 25

This means that Charlie will get 15 sweets and David will get 25 sweets.

There can be ratio word problems involving different operations and types of numbers.

Here are some examples of different types of ratio word problems:

Common Core State Standards

How does this relate to 6 th and 7 th grade math?

• Grade 6 – Ratios and Proportional Relationships (6.RP.A.3) Use ratio and rate reasoning to solve real-world and mathematical problems, for example, by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
• Grade 7 – Ratio and Proportional Relationships (7.RP.A.2) Recognize and represent proportional relationships between quantities.

How to do ratio problem solving

In order to solve problems including ratios:

Identify key information within the question.

Know what you are trying to calculate.

Use prior knowledge to structure a solution.

[FREE] Ratio Problem Solving Worksheet (Grade 6 to 8)

Use this worksheet to check your grade 6 to 8 students’ understanding of ratio problem solving. 15 questions with answers to identify areas of strength and support!

Ratio problem solving examples

Example 1: part:part ratio.

Within a school, the total number of students who have school lunches to packed lunches is 5 : 7. If 465 students have a school lunch, how many students have a packed lunch?

Within a school, the number of students who have school lunches to packed lunches is \textbf{5 : 7} . If \textbf{465} students have a school lunch, how many students have a packed lunch?

Here you can see that the ratio is 5 : 7, where the first part of the ratio represents school lunches (S) and the second part of the ratio represents packed lunches (P).

You could write this as:

Where the letter above each part of the ratio links to the question.

You know that 465 students have school lunch.

2 Know what you are trying to calculate.

From the question, you need to calculate the number of students that have a packed lunch, so you can now write a ratio below the ratio 5 : 7 that shows that you have 465 students who have school lunches, and p students who have a packed lunch.

You need to find the value of p.

3 Use prior knowledge to structure a solution.

You are looking for an equivalent ratio to 5 : 7. So you need to calculate the multiplier.

You do this by dividing the known values on the same side of the ratio by each other.

465\div 5 = 93

This means to create an equivalent ratio, you can multiply both sides by 93.

So the value of p is equal to 7 \times 93=651.

There are 651 students that have a packed lunch.

Example 2: unit conversions

The table below shows the currency conversions on one day.

Use the table above to convert £520 \; (GBP) to Euros € \; (EUR).

Use the table above to convert \bf{￡520} \textbf{ (GBP)} to Euros \textbf{€ } \textbf{(EUR)}.

The two values in the table that are important are \text{GBP} and EUR. Writing this as a ratio, you can state,

You know that you have £520.

You need to convert GBP to EUR and so you are looking for an equivalent ratio with GBP=£520 and EUR=E.

To get from 1 to 520, you multiply by 520 and so to calculate the number of Euros for £520, you need to multiply 1.17 by 520.

1.17 \times 520=608.4

So £520=€608.40.

Example 3: writing a ratio 1 : n

Liquid plant food is sold in concentrated bottles. The instructions on the bottle state that the 500 \, ml of concentrated plant food must be diluted into 2 \, l of water. Express the ratio of plant food to water, respectively, in the ratio 1 : n.

Liquid plant food is sold in concentrated bottles. The instructions on the bottle state that the \bf{500 \, ml} of concentrated plant food must be diluted into \bf{2 \, l} of water. Express the ratio of plant food to water respectively as a ratio in the form 1 : n.

Using the information in the question, you can now state the ratio of plant food to water as 500 \, ml : 2 \, l. As you can convert liters into milliliters, you could convert 2 \, l into milliliters by multiplying it by 1000.

2 \, l=2000 \, ml

So you can also express the ratio as 500 : 2000 which will help you in later steps.

You want to simplify the ratio 500 : 2000 into the form 1:n.

You need to find an equivalent ratio where the first part of the ratio is equal to 1. You can only do this by dividing both parts of the ratio by 500 (as 500 \div 500=1 ).

So the ratio of plant food to water in the form 1 : n is 1 : 4.

Example 4: forming and solving an equation

Three siblings, Josh, Kieran and Luke, receive an allowance each week proportional to their age. Kieran is 3 years older than Josh. Luke is twice Josh’s age. If Josh receives \$ 8 allowance, how much money do the three siblings receive in total?

Three siblings, Josh, Kieran and Luke, receive an allowance each week proportional to their ages. Kieran is \bf{3} years older than Josh. Luke is twice Josh’s age. If Luke receives \bf{\$ 8} allowance, how much money do the three siblings receive in total?

You can represent the ages of the three siblings as a ratio. Taking Josh as x years old, Kieran would therefore be x+3 years old, and Luke would be 2x years old. As a ratio, you have:

You also know that Luke receives \$ 8.

You want to calculate the total amount of allowance for the three siblings.

You need to find the value of x first. As Luke receives \$ 8, you can state the equation 2x=8 and so x=4.

Now you know the value of x, you can substitute this value into the other parts of the ratio to obtain how much money the siblings each receive.

The total amount of allowance is therefore 4+7+8=\$ 19.

Example 5: simplifying ratios

Below is a bar chart showing the results for the colors of counters in a bag.

Express this data as a ratio in its simplest form.

From the bar chart, you can read the frequencies to create the ratio.

You need to simplify this ratio.

To simplify a ratio, you need to find the highest common factor of all the parts of the ratio. By listing the factors of each number, you can quickly see that the highest common factor is 2.

\begin{aligned} & 12 = 1, {\color{red}2}, 3, 4, 6, 12 \\\\ & 16 = 1, {\color{red}2}, 4, 8, 16 \\\\ & 10 = 1, {\color{red}2}, 5, 10 \end{aligned}

HCF(12,16,10) = 2

Dividing all the parts of the ratio by 2, you get

Our solution is 6 : 8 : 5.

Example 6: combining two ratios

Glass is made from silica, lime and soda. The ratio of silica to lime is 15 : 2. The ratio of silica to soda is 5 : 1. State the ratio of silica:lime:soda.

Glass is made from silica, lime and soda. The ratio of silica to lime is \bf{15 : 2}. The ratio of silica to soda is \bf{5 : 1}. State the ratio of silica:lime:soda.

You know the two ratios

You are trying to find the ratio of all 3 components: silica, lime and soda.

Using equivalent ratios you can say that the ratio of Silica:Soda is equivalent to 15 : 3 by multiplying the ratio by 3.

You now have the same amount of silica in both ratios and so you can now combine them to get the ratio 15 : 2 : 3.

Example 7: using bar modeling

India and Beau share some popcorn in the ratio of 5 : 2. If India has 75 \, g more popcorn than Beau, what was the original quantity?

India and Beau share some popcorn in the ratio of \bf{5 : 2} . If India has \bf{75 \, g} more popcorn than Beau, what was the original quantity?

You know that the initial ratio is 5 : 2 and that India has three more parts than Beau.

You want to find the original quantity.

Drawing a bar model of this problem, you have:

Where India has 5 equal shares, and Beau has 2 equal shares.

Each share is the same value and so if you can find out this value, you can then find the total quantity.

From the question, India’s share is 75 \, g more than Beau’s share so you can write this on the bar model.

You can find the value of one share by working out 75 \div 3=25 \, g.

You can fill in each share to be 25 \, g.

Adding up each share, you get

India=5 \times 25=125 \, g

Beau=2 \times 25=50 \, g

The total amount of popcorn was 125+50=175 \, g.

Teaching tips for ratio problem solving

• Continue to remind students that when solving ratio word problems, it’s important to identify the quantities being compared and express the ratio in its simplest form.
• Create practice problems for students using the information in your classroom. For example, ask students to find the ratio of boys to the ratio of girls using the total number of students in your classroom, then the school.
• To find more practice questions, utilize educational websites and apps instead of worksheets. Some of these may also provide tutorials for struggling students. These can also be helpful for test prep as they are more engaging for students.
• Use a variety of numbers in your ratio word problems – whole numbers, fractions, decimals, and mixed numbers – to give students a variety of practice.
• Provide students with a step-by-step process for problem solving, like the one shown above, that can be applied to every ratio word problem.

Easy mistakes to make

• Mixing units Make sure that all the units in the ratio are the same. For example, in example 6, all the units in the ratio were in milliliters. You did not mix ml and l in the ratio.
• Writing ratios in the wrong order For example, the number of dogs to cats is given as the ratio 12 : 13 but the solution is written as 13 : 12.

• Counting the number of parts in the ratio, not the total number of shares For example, the ratio 5 : 4 has 9 shares, and 2 parts. This is because the ratio contains 2 numbers but the sum of these parts (the number of shares) is 5+4=9. You need to find the value per share, so you need to use the 9 shares in your next line of working.
• Ratios of the form \bf{1 : \textbf{n}} The assumption can be incorrectly made that n must be greater than 1, but n can be any number, including a decimal.

Related ratio lessons

• Unit rate math
• Simplifying ratios
• Ratio to fraction
• How to calculate exchange rates
• Ratio to percent
• How to write a ratio
• Dividing ratios
• How to find the unit rate
• Ratio scale
• Constant of proportionality

Practice ratio problem solving questions

1. An online shop sells board games and computer games. The ratio of board games to the total number of games sold in one month is 3 : 8. What is the ratio of board games to computer games?

8-3=5 computer games sold for every 3 board games.

2. The ratio of prime numbers to non-prime numbers from 1-200 is 45 : 155. Express this as a ratio in the form 1 : n.

You need to simplify the ratio so that the first number is 1. That means you need to divide each number in the ratio by 45.

45 \div 45=1

155\div{45}=3\cfrac{4}{9}

3. During one month, the weather was recorded into 3 categories: sunshine, cloud and rain. The ratio of sunshine to cloud was 2 : 3 and the ratio of cloud to rain was 9 : 11. State the ratio that compares sunshine:cloud:rain for the month.

3 \times S : C=6 : 9

4. The angles in a triangle are written as the ratio x : 2x : 3x. Calculate the size of each angle.

You should know that the 3 angles in a triangle always equal 180^{\circ}.

\begin{aligned} & x+2 x+3 x=180 \\\\ & 6 x=180 \\\\ & x=30^{\circ} \\\\ & 2 x=60^{\circ} \\\\ & 3 x=90^{\circ} \end{aligned}

5. A clothing company has a sale on tops, dresses and shoes. \cfrac{1}{3} of sales were for tops, \cfrac{1}{5} of sales were for dresses, and the rest were for shoes. Write a ratio of tops to dresses to shoes sold in its simplest form.

\cfrac{1}{3}+\cfrac{1}{5}=\cfrac{5+3}{15}=\cfrac{8}{15}

1-\cfrac{8}{15}=\cfrac{7}{15}

6. The volume of gas is directly proportional to the temperature (in degrees Kelvin). A balloon contains 2.75 \, l of gas and has a temperature of 18^{\circ}K. What is the volume of gas if the temperature increases to 45^{\circ}K?

The given ratio in the word problem is 2. 75 \mathrm{~L}: 18^{\circ} \mathrm{K}

Divide 45 by 18 to see the relationship between the two temperatures.

45 \div 18=2.5

45 is 2.5 times greater than 18. So we multiply 2.75 by 2.5 to get the amount of gas.

2.75 \times 2.5=6.875 \mathrm{~l}

Ratio problem solving FAQs

A ratio is a comparison of two or more quantities. It shows how much one quantity is related to another.

A recipe calls for 2 cups of flour and 1 cup of sugar. What is the ratio of flour to sugar? (2 : 1)

In middle school ( 7 th grade and 8 th grade), students transition from understanding basic ratios to working with more complex and real-life applications of ratios and proportions. They gain a deeper understanding of how ratios relate to different mathematical concepts, making them more prepared for higher-level math topics in high school.

The next lessons are

• Converting fractions, decimals and percentages

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Algebra: Ratio Word Problems

Related Pages Two-Term Ratio Word Problems More Ratio Word Problems Algebra Lessons

In these lessons, we will learn how to solve ratio word problems that have two-term ratios or three-term ratios.

Ratio problems are word problems that use ratios to relate the different items in the question.

The main things to be aware about for ratio problems are:

• Change the quantities to the same unit if necessary.
• Write the items in the ratio as a fraction .
• Make sure that you have the same items in the numerator and denominator.

Ratio Problems: Two-Term Ratios

Example 1: In a bag of red and green sweets, the ratio of red sweets to green sweets is 3:4. If the bag contains 120 green sweets, how many red sweets are there?

Solution: Step 1: Assign variables: Let x = number of red sweets.

Step 2: Solve the equation. Cross Multiply 3 × 120 = 4 × x 360 = 4 x

Answer: There are 90 red sweets.

Example 2: John has 30 marbles, 18 of which are red and 12 of which are blue. Jane has 20 marbles, all of them either red or blue. If the ratio of the red marbles to the blue marbles is the same for both John and Jane, then John has how many more blue marbles than Jane?

Solution: Step 1: Sentence: Jane has 20 marbles, all of them either red or blue. Assign variables: Let x = number of blue marbles for Jane 20 – x = number red marbles for Jane

Step 2: Solve the equation

Cross Multiply 3 × x = 2 × (20 – x ) 3 x = 40 – 2 x

John has 12 blue marbles. So, he has 12 – 8 = 4 more blue marbles than Jane.

Answer: John has 4 more blue marbles than Jane.

How To Solve Word Problems Using Proportions?

This is another word problem that involves ratio or proportion.

Example: A recipe uses 5 cups of flour for every 2 cups of sugar. If I want to make a recipe using 8 cups of flour. How much sugar should I use?

How To Solve Proportion Word Problems?

When solving proportion word problems remember to have like units in the numerator and denominator of each ratio in the proportion.

• Biologist tagged 900 rabbits in Bryer Lake National Park. At a later date, they found 6 tagged rabbits in a sample of 2000. Estimate the total number of rabbits in Bryer Lake National Park.
• Mel fills his gas tank up with 6 gallons of premium unleaded gas for a cost of $26.58. How much would it costs to fill an 18 gallon tank? 3 If 4 US dollars can be exchanged for 1.75 Euros, how many Euros can be obtained for 144 US dollars?

Ratio problems: Three-term Ratios

Example 1: A special cereal mixture contains rice, wheat and corn in the ratio of 2:3:5. If a bag of the mixture contains 3 pounds of rice, how much corn does it contain?

Solution: Step 1: Assign variables: Let x = amount of corn

Step 2: Solve the equation Cross Multiply 2 × x = 3 × 5 2 x = 15

Answer: The mixture contains 7.5 pounds of corn.

Example 2: Clothing store A sells T-shirts in only three colors: red, blue and green. The colors are in the ratio of 3 to 4 to 5. If the store has 20 blue T-shirts, how many T-shirts does it have altogether?

Solution: Step 1: Assign variables: Let x = number of red shirts and y = number of green shirts

Step 2: Solve the equation Cross Multiply 3 × 20 = x × 4 60 = 4 x x = 15

5 × 20 = y × 4 100 = 4 y y = 25

The total number of shirts would be 15 + 25 + 20 = 60

Answer: There are 60 shirts.

Algebra And Ratios With Three Terms

Let’s study how algebra can help us think about ratios with more than two terms.

Example: There are a total of 42 computers. Each computer runs one of three operating systems: OSX, Windows, Linux. The ratio of the computers running OSX, Windows, Linux is 2:5:7. Find the number of computers that are running each of the operating systems.

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Praxis Core Math

Course: praxis core math   >   unit 1.

• Rational number operations | Lesson
• Rational number operations | Worked example

Ratios and proportions | Lesson

• Ratios and proportions | Worked example
• Percentages | Lesson
• Percentages | Worked example
• Rates | Lesson
• Rates | Worked example
• Naming and ordering numbers | Lesson
• Naming and ordering numbers | Worked example
• Number concepts | Lesson
• Number concepts | Worked example
• Counterexamples | Lesson
• Counterexamples | Worked example
• Pre-algebra word problems | Lesson
• Pre-algebra word problems | Worked example
• Unit reasoning | Lesson
• Unit reasoning | Worked example

What are ratios and proportions?

What skills are tested.

• Identifying and writing equivalent ratios
• Solving word problems involving ratios
• Solving word problems using proportions

How do we write ratios?

• The ratio of lemon juice to sugar is a part-to-part ratio. It compares the amount of two ingredients.
• The ratio of lemon juice to lemonade is a part-to-whole ratio. It compares the amount of one ingredient to the sum of all ingredients.
• Determine whether the ratio is part to part or part to whole.
• Calculate the parts and the whole if needed.
• Plug values into the ratio.
• Simplify the ratio if needed. Integer-to-integer ratios are preferred.
• 1 5 ‍   of the students on the varsity soccer team are lower-level students.
• 1 ‍   in 5 ‍   students on the varsity soccer team are lower-level students.

How do we use proportions?

• Write an equation using equivalent ratios.
• Plug in known values and use a variable to represent the unknown quantity.
• If the numeric part of one ratio is a multiple of the corresponding part of the other ratio, we can calculate the unknown quantity by multiplying the other part of the given ratio by the same number.
• If the relationship between the two ratios is not obvious, solve for the unknown quantity by isolating the variable representing it.
• (Choice A)   1 : 4 ‍   A 1 : 4 ‍  
• (Choice B)   1 : 2 ‍   B 1 : 2 ‍  
• (Choice C)   1 : 1 ‍   C 1 : 1 ‍  
• (Choice D)   2 : 1 ‍   D 2 : 1 ‍  
• (Choice E)   4 : 1 ‍   E 4 : 1 ‍  
• (Choice A)   1 6 ‍   A 1 6 ‍  
• (Choice B)   1 3 ‍   B 1 3 ‍  
• (Choice C)   2 5 ‍   C 2 5 ‍  
• (Choice D)   1 2 ‍   D 1 2 ‍  
• (Choice E)   2 3 ‍   E 2 3 ‍  
• Your answer should be
• an integer, like 6 ‍  
• a simplified proper fraction, like 3 / 5 ‍  
• a simplified improper fraction, like 7 / 4 ‍  
• a mixed number, like 1   3 / 4 ‍  
• an exact decimal, like 0.75 ‍  
• a multiple of pi, like 12   pi ‍   or 2 / 3   pi ‍  

Things to remember

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